Frequency conversion Items tagged with Frequency conversion

I need to monitor a +7V input with variable frequency - is it possible to sample the frequency on a 8051 without additional hardware?

I need this to log revolutions of an engine. Output is as said +7V, when the engine is idling output is 26Hz (approx. 750rpm). So basically I need to translate the frequency of the input to a given value. Is it possible?